DeBoer Seaview

[Subculture]

It's just a variation on a theme.

You could incorporate such a system into your tank design, just needs a bit of jiggery pokery.

[LOFTDRIVER]

The Beast is back

I was just thinking to myself this lunch time about the surface trim of this boat.I am probably going to offend some of you with this but if it has the effect of a debait about this subject then so be it.I have at home a video taken at a show in the states of a Seview model running and diving with the super high free board that is seen in the film and some of the tv show.This model seemed to take forever to dive and looked like it did not enjoy the experiance at all,it had a nice dived trim but looked far from happy about being at depth.On the surface it looked more at home.I notice that the surface trim of Davids boat is a lot lower is this by design? or down to the size of ballast tank used?The water line that david has on his boat also turns up on the tv show in shots by a navy base.The water line I have on my boat is what I think of as normal water line for a model of this type.Is there a way to come up with the water line for this boat or is it going to be up to the individual to what he can get his boat to work at.I think that it will be the later but it will be nice to no what everone thinks on this subject.
Loftdriver out

[ADDINGTON]

If you are seeking opinions,since no one has yet produced a working diveable 80, I could not find fault with anyone who achieves the feat with any reasonable surfaced waterline.
In my case, I am merely starting with a goal of seeing as much of the bow windows exposed as possible.
Since we're talking about Seaview, is there really any "correct" surfaced trim ?

[Subculture]

Waterline is just a function of

1. Size of ballast tank and how much room you have to stow one.
2. Volume of hull above the waterline. Thickly laminated hulls need bigger ballast tanks.

Dive time is a function of

1. Type of pump (air or water)
2. Size of valves to vent air or water.

The type of pumps I have described (Whale or Reich) will empty a tank of about 3 litres volume in under 15 seconds, and that's quite fast enough IMO. If you want a bigger tank, then you could add two pumps working parallel, or fit a bigger pump, or accept a slightly longer dive time.

The important thing for such a big boat is independent control of main ballast and trim ballast, because being such a large vessel, small changes in water density will have a big impact on the trim of your boat.

[seaview]

hi guys
The water line changed in each show. If you get too high the seaview will be top heavy and the manta fins will dig in when you turn the sub.
A water line at mid window ( on the 4 window hull ) seems to be more stable. we must remember that this is not a real submarine,
if it was the U S Navy would have one. I have seen this same thing with the 66"nautilus. If you dream it do it!
When the Seaview shot torpedoes, where did they come from?


seaview

[greenman407]

Kerry, What an awesome build you have going there, I just read thru the whole thing and stole a bunch of pictures. Looks to me like that there is no way you can fail because you have so many people behind you! It was nice talking with you by phone today. Ill be in touch. :biggrin:

[ADDINGTON]

So far I've only offered a ballast tank, but as the weather warms hopefully all the posters here can continue to share ideas, get these hulls wet and hopefully we will make 2010 the year of the 80 !
-Kerry

[Scott T]

Check out the valve on a large detergent bottle for a possible ballast tank drain valve. Parts of it might work for a
valve under low pressure.



Scott

[LOFTDRIVER]

The Beast is back

As the winter has finally gone and the loft has been cleared it is time to start work on the beast.I have got here back on the work bench and have started work on firming up the control links that were a bit to slack for my taste.The other question that has been raised is the size and mode of ballast tank.I have in my spares box three 825 size Engal tanks.I am thinking of using one of these and also a compreased air system.The thinking so far goes like this flood two tanks either side of a central engal tank.The idea is to take the boat down to a just afoat leavel with the air tanks and then final trim with the more controled Engal tank.The question I need an answer to is can an Engal tank be used in a free flood area.As long as the working end is in a water tight compartment does it matter if the rest of it is in the water.I have never seen this done .Please any help will be of great value.
Loftdriver out

[He Who Shall Not Be Named]

You are making this system much, much harder and difficult to maintain than it has to be.

But, to address your specific question:

Yes, you can put the piston tank assembly in the wet if (as you point out) you keep the motor, switches, controller, and attached gear-train in the dry. But, you will have to insure that you port the displaced air from the dry-side of the piston to a watertight space of sufficient volume to be compressed to not too high a pressure when the piston(s) go to the 'flood' position.

Your proposed arrangement is overly complicated, redundant, and stupid. Don't do it.

David,

[Albion]

The question I need an answer to is can an Engal tank be used in a free flood area.As long as the working end is in a water tight compartment does it matter if the rest of it is in the water.I have never seen this done .Please any help will be of great value.
Loftdriver out

potentially yes, but how will you get a good seal on the outside of the tank. When the piston moves it pressurises the WTC, and that will probably blow your ballast tank off the end of the wTC.

[Subculture]

A very nice 205 class built by Nigel Edmonds uses two piston tanks mounted inside a central main ballast tank. This tank is emptied and filled using a peristalitic pump, which is set-up to suck the air out of the tank. There is no exposed water surface- neutral and negative trim is taken care of by the two piston tanks, which are servo controlled.

Anyone who has seen this boat will testify that it moves up and down statically like an elevator, and hovers at any height.

Modifying the Engel tanks to fit will not be difficult. If you're using compressed air, and the piston tank for trim then you could reduce the length of the tank to give 10-15% of the overall ballast volume. If you use a single tank then this is likely to result in a shifting C.G so you might want to consider a movable battery connected to servo. Or fit twin piston trim tanks like the German modellers do with their big 'pressluft' boats.

[greenman407]

Kerry, I dont want to get off of the present subject but in the past you have talked about some Seaviews tendancy to dive when underway. I just stumbled across this picture of my Seaview taken a couple of years ago. Perhaps you can tell something by the shape of the manta fins where they join the nose.

[ADDINGTON]

Mark,
As I have no practical experience with this hull form,
any comment I have made about any Seaview running tendencies are purely paraphrasing of commentary by builders/runners like yourself.
Not sure what you mean about the fin/nose. Elaborate? I'm missing the obvious as usual!

[greenman407]

You earlier had mentioned to me that an aquaintance had viewed your Seaview and remarked that the way the bottom of the hull meets the top at the nose would determine its tendency to dive on its own or not. That is why early in your posts you showed a picture of the nose of your Seaview to illustrate the point, if memory serves.